diff mbox series

ifcvt: Don't speculation move inline-asm [PR102150]

Message ID 20250212043806.208724-1-quic_apinski@quicinc.com
State Committed
Headers
Series ifcvt: Don't speculation move inline-asm [PR102150] |

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Commit Message

Andrew Pinski Feb. 12, 2025, 4:38 a.m. UTC 
  So unlike loop invariant motion, moving an inline-asm out of an
if is not always profitable and the cost estimate for the instruction
inside inline-asm is unknown.

This is a regression from GCC 4.6 which didn't speculatively move inline-asm
as far as I can tell.
Bootstrapped and tested on x86_64-linux-gnu.

	PR rtl-optimization/102150
gcc/ChangeLog:

	* ifcvt.cc (cheap_bb_rtx_cost_p): Return false if the insn
	has an inline-asm in it.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
---
 gcc/ifcvt.cc | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Richard Biener Feb. 12, 2025, 8:51 a.m. UTC | #1 
On Wed, Feb 12, 2025 at 5:39 AM Andrew Pinski <quic_apinski@quicinc.com> wrote:
>
> So unlike loop invariant motion, moving an inline-asm out of an
> if is not always profitable and the cost estimate for the instruction
> inside inline-asm is unknown.
>
> This is a regression from GCC 4.6 which didn't speculatively move inline-asm
> as far as I can tell.
> Bootstrapped and tested on x86_64-linux-gnu.

OK.

Thanks,
Richard.

>         PR rtl-optimization/102150
> gcc/ChangeLog:
>
>         * ifcvt.cc (cheap_bb_rtx_cost_p): Return false if the insn
>         has an inline-asm in it.
>
> Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
> ---
>  gcc/ifcvt.cc | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/gcc/ifcvt.cc b/gcc/ifcvt.cc
> index cb5597bc171..707937ba2f0 100644
> --- a/gcc/ifcvt.cc
> +++ b/gcc/ifcvt.cc
> @@ -166,6 +166,12 @@ cheap_bb_rtx_cost_p (const_basic_block bb,
>      {
>        if (NONJUMP_INSN_P (insn))
>         {
> +         /* Inline-asm's cost is not very estimatable.
> +            It could be a costly instruction but the
> +            estimate would be the same as a non costly
> +            instruction.  */
> +         if (asm_noperands (PATTERN (insn)) >= 0)
> +           return false;
>           int cost = insn_cost (insn, speed) * REG_BR_PROB_BASE;
>           if (cost == 0)
>             return false;
> --
> 2.43.0
>
diff mbox series

Patch

diff --git a/gcc/ifcvt.cc b/gcc/ifcvt.cc
index cb5597bc171..707937ba2f0 100644
--- a/gcc/ifcvt.cc
+++ b/gcc/ifcvt.cc
@@ -166,6 +166,12 @@  cheap_bb_rtx_cost_p (const_basic_block bb,
     {
       if (NONJUMP_INSN_P (insn))
 	{
+	  /* Inline-asm's cost is not very estimatable.
+	     It could be a costly instruction but the
+	     estimate would be the same as a non costly
+	     instruction.  */
+	  if (asm_noperands (PATTERN (insn)) >= 0)
+	    return false;
 	  int cost = insn_cost (insn, speed) * REG_BR_PROB_BASE;
 	  if (cost == 0)
 	    return false;